Free - the man accused of being an al-Qaida leader, aka 'Q'

A man who was accused of being one of al-Qaida's leaders in Britain and who is alleged to have sent one of the July 7 suicide bombers to a terrorism training camp in Pakistan is living freely in the home counties and is not facing any charges.

According to evidence brought before the Old Bailey jury in the fertiliser bomb plot trial, Mohammed Quayyum Khan, a part-time taxi driver from Luton, is in direct contact with one of Osama bin Laden's most senior lieutenants.

Quayyum, known as "Q" to his alleged al-Qaida associates, is also accused of being the leader of a group of would-be terrorists whose plot to bomb London was foiled 18 months before the 7/7 attacks.

Among the allegations against Q during the year-long trial were that he was:

· the emir, or leader, of a group planning to use a massive fertiliser bomb to attack the Bluewater shopping centre in Kent, the Ministry of Sound nightclub in London, or high-pressure gas pipelines around the south-east

· instrumental in arranging for Mohammad Sidique Khan to travel to Pakistan, where he attended a terrorism training camp, in 2003

· a provider of funds and equipment for jihadi militants fighting American forces in Afghanistan

The counter-terrorism operation that culminated in yesterday's court case is understood to have begun with an MI5 investigation into Q in 2003. Despite the number of serious allegations levelled against him at the Old Bailey , police and MI5 say they have never found sufficient evidence to arrest or charge him.

His home has been searched at least once; neighbours have said police tore up floorboards and dug up his garden. However, there appears to be no plan to question him about his alleged link with the men who killed 52 people and injured more than 700 in the London bombings.

Q is in his 40s and married with several children. In recent years he has also used at least three other names similar to Quayyum. He is said to be a former associate of the fundamentalist clerics Omar Bakri Mohammed and Abu Hamza , and is said to have arranged for Bakri to speak in Luton before the preacher was banned from re-entering the UK in after the 7/7 attacks.

Haji Sulaiman, former president of Luton Central mosque, said Q had "brought Omar Bakri [Mohammed] to Luton". He added: "I didn't let him [Omar Bakri] come in our mosque. I didn't like those guys."

Today Q lives in a rented semi-detached house in Luton. Until recently he was working as a part-time taxi driver, and a Guardian journalist has also seen him working as a chef in a small cafe . When approached, he denied he was Q. He is thought to have since disappeared.

He is thought to have been born in Pakistan, a country he has visited often in recent years. The Old Bailey heard that during one trip in 2003 he was followed by the Pakistani intelligence agency, the ISI. The agents are said to have tracked him overtly to let him know they were aware of his presence there.

He was said in court to be taking orders from a senior al-Qaida figure in Pakistan called Abdul Hadi. He is understood to be Abdul Hadi al-Iraqi who, according to reports in the US, is a Kurd who served as an officer in Saddam Hussein's army. He is said to be a confidant of Bin Laden, and to have acted as an emissary to Abu Musab al- Zarqawi, al-Qaida's leader in Iraq. Iraqi was named by the US state department as a terror suspect shortly after the 9/11 attacks. The US government revealed last Friday that he had been captured several months ago and sent to Guantánamo Bay.

Q's alleged relationship with a senior al- Qaida fi gure was claimed by Mohammed Junaid Babar, a member of the fertiliser bomb gang who turned informant after being arrested by the FBI in New York.

Babar told the Old Bailey jury: "Hadi is just giving orders, but underneath Hadi there would be different, I guess you would call it cells, and this was a particular cell. The ultimate emir on top was Hadi. But underneath him there were multiple emirs, three or four emirs, before you reached Abdul Hadi, and Q was one of those emirs."

Babar told the court he had met one of the defendants in the fertiliser plot trial, Salahuddin Amin, at Islamabad airport, where Amin was waiting to meet two British jihadists who had been sent to Pakistan by Q on a "fact finding" mission. Babar said he knew the pair by their noms de guerre, Ibrahim and Zubair. The trial judge ruled that the jury should not be allowed to learn that Ibrahim was actually Sidique Khan, as that fact could prejudice them against the defendants.

Babar said that he, "Ibrahim", and others had driven to a terror training camp, collecting chemicals to make explosives en route, and spent a month learning how to assemble bombs and fire weapons. The court also heard that two young associates of Q from Luton were killed while fighting for the Taliban in Aghanistan in 2001.

While a number of the fertiliser bomb gang admitted knowing Q, his role was disputed during the trial. Amin told the court he had met Q when they were working as taxi drivers in Luton, and that Q was a family friend. He told police Q had sent money and equipment to jihadists in Pakistan, but claimed in court that he made this admission only because he had earlier been tortured for 10 months by the ISI.

He denied that Babar had been present when he met Sidique Khan and denied taking him to a terrorism training camp. The man who was to go on to lead the 7/7 bombers had been sent to him by "brothers in Luton", he told the court, but could not say who they were.

Amin also denied Babar's claim that Q was his emir. Several defence lawyers condemned Babar's account as a concoction of "elaborate lies", saying he was an FBI double agent or that he invented the plot to get a reduced sentence in the U S, where he has admitted terrorist offences.

Prosecution lawyers, on the other hand, said Babar that had been an "impressive, truthful and accurate" witness.

The court also heard that a number of meetings in the UK between Q and one of the defendants, Omar Khyam, had been secretly filmed by MI5, who gave Q the codename Bashful Dwarf.

During cross-examination, Khyam admitted meeting Q shortly before he was about to leave the country . "He gave me money," he told the court. "He said, 'It's better for both of us if we don't meet each other.' Because the security services may be monitoring me." Khyam refused to say how he first met Q, or discuss his role.

Scotland Yard and the security service maintain that there is insufficient evidence to bring charges against Q. The Guardian has repeatedly tried to speak to Mohammed Quayyum Khan about the allegations that were made in court. He has declined to comment.